I tried this 3M headlamp restore kit and it worked perfect. See pic link for "before & after". Almost forgot what the headlamps originally looked like under all that yellow haze! Makes a big difference as far as it not looking its age... kind like "a touch of gray" for men!

Kit had a few different grit disc pads, a final wet sand pad and a polish/buff pad with a packet of their polish and also a drill attachment with velcro to quick attach/remove pads. Actually went really quick and easy with my DeWalt 18v drill. Much easier if lenses are removed so you don't risk scuffing the surrounding paint but that takes more time and I need a paint job anyways so I went with the quick n easy route. They say to mask around the lens with 2 layers of tape to help protect the paint but I skipped that part also and went reeeeeeally carefully around the lenses.

I guess a good wax polish would help protect it after the buffing which i will soon do. I saw one guy spray coat the lenses with a UV clear coat after the 3M buffing, then polished the clear coat then waxed it.... all fine and good if you have the time.